Drive coupling for drill string



Dec. 13, 1966 c. D. FORAN 392919225 DRIVE COUPLING FOR DRILL STRING Filed July 5, 1964 2 Sheets- Shem l iiiFiin K 5 EFL? INVENTOR. CHARLES D. FO/M/V BY z/M aem m TTOfP/VEY Dec. 13, 1966 c. D. FORANR 9 -9 DRIVE COUPLING FOR DRILL STRING Filed July 5, 1964 2 Sheets-Sheet 2 United States Patent G 3,291,225 DRIVE COUPLING FOR DRILL STRING Charles D. Foran, Dallas, Tex., assignor to Gardner- Denver Company, a corporation of Delaware Filed July 3, 1964, Ser. No. 380,137 7 Claims. (Cl. 173164) The present invention generally pertains to an earth drilling rig and more particularly to a rig which employs a drill string made up of two or more threadably joined sections of pipe or rod.

This invention is especially applicable to so-called topdrive rigs wherein the operating forces for rotating and for raising and lowering the drill string are applied to the top of the uppermost section of the drill string by a rotary.

drive unit mounted for powered up and down movement along an upstanding frame or mast. Commonly, the rotary drive unit is threadably connected to the uppermost pipe or rod section and the drill string is made up by threadably joining several pipe sections in end-toend relation as drilling proceeds to a desired depth. Thus, after the first pipe section has penetrated the ground to a predetermined depth, the rotary drive unit is operated in a reverse direction to unscrew the same from the top of the first pipe section. The rotary drive unit is then raised within the mast and a second pipe section is threadably joined between the rotary drive unit and the top of the first pipe section. When not in use the several sections of pipe which go to make up the drill string may be stored in a pipe handling rack which is operable for individually positioning the stored pipe sections in line with the rotary drive unit and the hole. Such use of a pipe handling rack eliminates laborious manual handling of heavy pipe sections and reduces drilling time and costs. In coming out of the hole, the entire drill string is first raised until the joint between the uppermost pipe section and the next lower section is exposed. A suitable wrench means is applied below this joint to support the lower pipe section and the remainder of the drill string; and, the rotary drive unit is then reversely rotated to break and unscrew this joint. The pipe rack is then positioned in line with the hole to receive the disconnected pipe section and, after this section is unscrewed at its top from the rotary drive unit, the pipe rack containing the disconnected pipe section is moved out of line with the hole so that the rotary drive unit may be lowered to thread into the top of the next lower pipe section of the drill string and raise the same within the mast for uncoupling. This sequence of uncoupling operations is repeated until the drill string is completely disassembled and the several pipe sections are stored in the pipe rack.

From the foregoing brief description of the usual mode of operation of drill rigs of the type presently under consideration, it will be understood that, in coming out of the hole, some means must be provided to insure that that pipe section being removed from the drill string will unscrew at the joint with the next lower pipe section and not at the upper joint with the rotary drive unit. Unless some means is provided for this purpose, there exists an equal likelihood that the upper joint between the pipe section and the rotary drive unit will be uncoupled upon reverse rotation of the rotary drive unit. If the upper joint breaksfirst, time will be lost in remedying the situation; moreover, should the upper joint completely uncouple, the upper pipe section, being laterally supported only by the threaded joint at its lower end, may fall against the mast or damage the threads of the joint at its lower end. Since the joint between the pipe section and the rotary drive unit is located near the top of the mast during this crucial uncoupling operation, manual application of wrench means for securing this joint is impractical and especially dangerous to the workman on the mast and those below. Although remotely controlled automatic wrench means for securing the upper joint against unintended uncoupling have been proposed, these devices are usually very complex and, therefore, costly to manufacture and maintain.

Therefore, a general object of this invention is to provide a coupling device for a top-drive drilling rig which will permit the rig operator to unscrew a pipe section at a preselected joint thereby eliminating the aforementioned problems and risks heretofore encountered in disassembling a drill string.

Another object is to provide a coupling device of the aforedescribed type which is particularly adapted to perform these functions:

(1) Provide a forward driving connection between the rotary drive unit and the upper pipe section when the drill string is being assembled and during drilling operations;

(2) Provide a positive reverse driving connection between the rotary drive unit and the upper pipe section during disassembly of the drill string thereby preventing unintended unscrewing of the upper pipe section from the rotary drive unit;

(3) Provide controllable means for releasing the aforementioned positive reverse driving connection thereby per- 'mitting intended unscrewing of the upper drill pipe from the rotary drive unit when the latter is reversely rotated.

A further object is to provide an extensible coupling which is capable of performing the aforestated functions and which is conditioned to perform a selected function by operator-controlled raising or lowering of the rotary drive unit with respect to the drill string.

A more specific object is to provide a coupling device which is threadably connectable in axial alignment between the rotary drive unit and the upper pipe section and which includes a telescoping wrench element con- 'trollably engageable with wrench flats located at the top of the upper pipe section to prevent unintended disassembly of the rotary drive unit and the upper pipe section.

A still more specific object is to provide a coupling device of the aforedescribed type which is characterized by simplicity and ruggedness of construction, rapid operation, and low cost of manufacture and maintenance.

These and other objects and advantages will become apparent upon reading the following description and claims in connection with the attached drawings in which:

MG. 1 is a fragmentary plan view of a top-drive drilling rig incorporating a coupling device which embodies the present invention;

FIG. 2 is a view of a pipe rack taken generally along lines 2--2 of FIG. 1 showing the rack in the out position in full lines and in the in position in phantom lines;

FIG, 3 is a view taken generally along lines 33 of FIG. 1;

FIGS. 4, Sand 6 are longitudinal and sectional views of the coupling device shown in FIG. 1 illustrating movable internal parts of the device in three relative positions;

FIG. 7 is a transverse section taken along lines 77 of FIG. 4;

FIG. 8 is a transverse section taken along lines 8-8 of FIG. 5;

FIG. 9 is a transverse section taken along lines 99 of FIG. 6; and

FIG. 10 is a transverse section taken along lines 101 0 of FIG. 4.

FIG.-l of the drawings shows a preferred embodiment of a coupling device, indicated in its entirely at numeral '3 O ficient. The rig 12 includes a horizontal deck 14 which is transported from place to place by suitable powered tracks 16 and is supported and leveled at a selected drilling site by extensible jacks 18. An upright mast 20 is carried at one end of the deck 14 and may be pivotally attached thereto to swing downwardly onto the deck to a transporting position. The mast 20 includes a base member 22, side frame members 24, 26 and a top frame member 28. Numeral 30 indicates a reversible rotary drive unit which is carried by a cross member 32 which traverses the mast 20 vertically. The cross member 32 and the attached drive unit 30 are raised and lowered within the mast 20 by operator-controlled power means 33 connecting with opposite ends of the cross member 32. The drive unit 30 may comprise an electric, pneumatic or hydraulic rotary actuator or an engine-driven transmission unit capable of developing the required torque and speed for drilling a selected earth formation.

Drilling is accomplished by a rotary bit or by an inthe-hole percussive tool, not shown, attached to the lower end of a drill string 34 which comprises a plurality of pipe sections or rod sections threadably joined in endto-end relation at spaced joints. During the drilling operation, the drill string 34 is rotated by the drive unit 30 which is drivably connected to the uppermost pipe section 36a by the aforementioned coupling device 10. To enhance the cutting action of the drill bit, pressure is applied to the top of the drill string 34 by the power means 33 which forcibly lowers the cross member 32 and drive unit 30. From the foregoing description, it will be understood by those familiar with drill rigs that the present rig is of the so-called top drive type wherein drilling rotation and pull down pressure are applied to the top of the drill string.

The illustrative drill string 34 is made up of identical pipe sections which comprise an upper section 36a, a next lower section 36b threadably joined to section 36a, and other sections hidden from view in the hole 38. Each pipe section may be as much as twenty feet in length and several inches in outside diameter; therefore, it will be appreciated that the individual sections are weighty and difficult to handle manually. For these reasons, a pipe rack 42 is provided to store four detached sections of the drill string and to position individually the stored sections in line with the rotary drive unit 30 and the hole 38 as more sections are added to the drill string 34 during the course of drilling. The rack 42 is conventionally constructed and, as shown in simplified form, comprises a center member 44 rotatably supported on upper and lower pivot arms 46 and 48 which are swingable with respect to the mast 20 about pivot members 50 and 52 attached to side frame member 26. Four angularly spaced pipe socket-s 54 are carried by a plate 56 fixed adjacent the lower end of the center member 44; and, as shown in connection with a pipe section 360, the sockets open upwardly to receive the bottom ends of the pipe sections stored in the rack. The top end of each stored pipe section is received and retained in one of four radially opening slots 58 in a retainer cover 60 fixed adjacent the upper end of the center member 44. As shown in phantom lines in FIG. 2, the pipe rack 42 may be manually or mechanically manipulated to rotate the center member 44 and to swing the same about the pivots 50 and 52 for positioning the stored pipe section 36c in alignment with the rotary driver 30.

As seen in FIG. in connection with the upper pipe section 36a, for example, the top portion of each pipe section is provided with two sets of longitudinally spaced, external flats 62a and 64a. The flats 62a extend to the extreme upper end surface of the pipe sections for a purpose to be described. The lower end of each pipe section is provided with a single set of flats 66a; and, a power cylinder 68 is mounted on the base member 22 of the mast 20 and is controllably extensible to bring a wrench head 70 into holding engagement with certain of the aforementioned pipe flats to prevent rotation of a selected pipe section during assembly and disassembly of the drill 34. The functions of the various pipe flats will be more fully set fort-h hereinafter in connection with the description of the operation of the drill rig 12.

The aforementioned Coupling device 10 is removably connected in axial alignment with the output shaft 72 of the rotary drive unit 30 by means of a threaded joint with an adapter 74. A set screw 76 radially penetrates the wall of the adapter 74 and seats in an annular groove 78 relieved in the external surface of the shaft 72 to prevent unintended disassembly of the adapter from the shaft upon reverse or unscrewing rotation of the rotary drive unit 30. Preferably the output shaft 72 and the adapter are provided with axial bores which comprise part of a passage from a fluid swivel joint 80 penetrating the rotary drive unit 30 through the coupling device 10 for conducting hole-flushing fluid downwardly to the central bore through the drill string 34. The upper end of a hollow drive sleeve 82 is nonrotatably connected to the lower end of the adapter 74 by interfering threads and is provided along its lower portion with external splines 84 and internal splines 86. A hollow drive shaft 88 is coaxially surrounded by the drive sleeve 82 and is provided with external splines 90 which interfit with the internal splines 86 to provide a rotary driving connection between sleeve 82 and shaft 88. However, the shaft 88 is axially s'hiftable with respect to the sleeve 82 between a lower position, shown in FIG. 4, and an upper position shown in FIG. 5. An enlarged head 92 on the upper end of the shaft 88 is reciprocable within an enlarged bore 94 of the sleeve 82 which serves as a guide for the head 92 and which is sealably engaged by an O-ring 96 carried by the head 92. The lower limiting position of the shaft 88 with respect to the sleeve 82 is established by abutment of the head 92 against an internal shoulder 98 at the lower end of the enlarged bore 94. By means of interfering threads, the lower end of the drive shaft 88 is nonrotatably joined to a cylindrical pipe sub 100 which, in turn, is removably attached by standard pipe threads to the upper pipe section 36a. As seen in FIG. 5, the upward movement of the shaft 88 with respect to sleeve 82 is limited by abutment of the upper end surface of the head 92 with the lower end of the adapter 74. As thus far described, it will be understood that the sleeve 82 and the drive shaft 88 are adapted for relative axial shifting between an extended position, shown in FIG. 4, and a collapsed position, shown in FIGS. 5 and 6, and that the described parts of the breakout device 10 provide a rotary driving connection between the rotary drive output shaft 72 and the pipe section 36a.

An important feature of the present invention is the provision of a telescoping wrench 102 which is held in relatively reciprocable, but nonrotatable relationship with the drive sleeve 82 by means of internal splines 104 which engage and interfit with the aforementioned external splines 84. The upper portion of the wrench 102 is provided with an exterior annular groove 106 defining shoulders 108 and 110. A split cylindrical sleeve 112 coaxially surrounds a portion of the drive sleeve 82 and an upper flanged portion 113 of the wrench 102 is disposed therebetween. An external annular groove 114 in the drive sleeve 82 has seated therein an internal flange portion 116 of the split sleeve 112; and, :as seen in FIG. 10, the respective halves of the split sleeve are secured together by suitable fasteners 118. An internal flange 120 adjacent the bottom of the split sleeve 112 interfits in the aforementioned annular groove 106 of the wrench 102 and abuts with the shoulders 108 and to limit relative axial movement between the drive sleeve 82 and the wrench. The depending portion 122 of the wrench 102 is provided with a central aperture 124 which, as shown in FIG. 9, has four wrench flats 126 which mate with the pipe flats 62a at the top of the upper pipe section 36a. The maximum outside diameter of the cylindrical sub 100 is less than the smallest cross sectional dimension of the wrench aperture 124 and is freely receivable therein. On the other hand, the cross sectional configuration of the wrench aperture 124 and the top of the pipe section 36a are geometrically similar, and the dimensions thereof vary only suificiently to permit the wrench 102 to shift down over the pipe section 360 when the wrench flats 126 are angularly aligned with the pipe flats 62a, as shown in FIG. 9. When the wrench is in the down or engaged position, shown in FIGS. 6 and 9, a rotary driving connection is established between the rotary drive output shaft 72 and the upper pipe section 36a by means of adapter 74, drive sleeve 82, splines 84 and 104, and the telescoping wrench 102.

The inventive characteristics of the present invention will be more fully appreciated from the following description of the operation of the drill rig 12. After the rig 12 is positioned at a selected drilling site and a first pipe section is connected to the pipe sub 100, the drive unit 30 is rotated in the forward or drilling direction and downward drilling pressure is applied to the cross member 32. If, when the first pipe section and sub 100 are fully threaded together, the pipe flats 62 at the top of the first pipe are angularly aligned with the wrench flats 126 of the telescoping wrench 102, the wrench will drop down over the upper end of the pipe sect-ion as shown in FIG. 1. However, if flats 62 and 126 are not aligned, the wrench 102 will be carried atop the pipe section as shown in FIG. 5. During the drilling operation, it is of no consequence if the wrench 102 fails to engage with the pipe flats 62 since a forward rotary driving connection will be established between the rotary drive unit 30 and the first pipe section by means of the adapter 74, the drive sleeve 82, splines 36 and 90, the drive shaft 88 and the pipe sub 100. During drilling the pull down force applied by power means 33 will be imparted to the upper pipe section through axial abutment of the drive shaft head 92 and the adapter 74 as seen in FIG. 5. After the first pipe section has reached a position corresponding to that of section 36b in FIG. l, the cylinder 68 is actuated to place the wrench head 70 on the flats 64b and the drive unit 30 is raised relative to the drill string to raise the drive sleeve '82 to the position shown in FIG. 4 thereby insuring that the telescoping wrench 102 is completely disengaged from the pipe flats 62. The drive unit 30 is then rotated in the reverse direction to unscrew the first pipe section from the pipe sub 100. After the drive unit 30 and coupling device are raised in the mast to a position to clear the top of the pipe rack 42, a second pipe section in the rack is swung into line with the pipe sub 100, the coupling device 10 is lowered, and the pipe su-b 100 is screwed into the top of the second section. The second ipe section is then raised to clear the pipe socket 54-, the pipe rack 42 is swung out to the full line position shown in FIG. 2, and the drive unit 30 is lowered and rotated to screw the second pipe section into the top of the first pipe section therebelow. The cylinder 68 is then actuated to withdraw the wrench head 70 from the first pipe section and the drilling operation recommences. In the same manner, additional pipe sections are attached between the coupling device 10 and the top of the drill string until the desired hole depth is reached.

The drill string 3.4 is withdrawn from the hole 38, disassembled, and stored in the rack 42 in the following manner. First the string is raised from the bottom of the hole by the power means 33 until the pipe sections 3611 and 36b reach the elevated position shown in FIG. 1. Due to the weight of the drill string, the coupling 10 will be extended as shown in FIG. 4 wherein the drive shaft 88 is supported by its headed end 02 and the wrench 102 drops downwardly until the shoulder 108 rests upon the flange 120 of the split sleeve 112. With the pipe sections 36:: and 36b positioned as shown in FIG. 1, the cylinder 68 is actuated to cause the wrench head 70 to engage flats 64b of pipe section 3612 to support the weight of the drill string and to prevent rotation of section 3612. Upon reverse or unscrewing rotation of the rotary drive unit 30, it is mandatory that the pipe section 36a be disconnected at its lower joint with pipe section 36b and not at its upper joint with the sub of the coupling device 10. If uncoupling of the upper joint should occur, these consequences would follow:

(1) Due to the substantial length of the section 36a it may bend or sway laterally about its lower end thereby damaging the mast 20 or the threads at the joint with section 36b.

(2) Since the driving connection with the rotary drive unit 30 would be broken, additional means would be required to rotate section 36a for unscrewing from section 3611.

(3) With the drive unit 30 disconnected from section 360, the power means 33 would be rendered useless for raising section 3601 within the mast so that the pipe rack 42 could be swung into pipe-receiving position.

(4) Generally the intended mode of operation of the drill rig 12 would be completely disrupted.

In order to avoid the above enumerated difficulties, the coupling device 10 is collapsed to the position shown in FIGS. 5 and 6, before the drive unit 30 is rotated in the reverse direction, by lowering the drive unit 30 until the lower end of the adapter 74 bears upon the upper end of the drive shaft 88. As the coupling 10 is collapsed from the condition shown in FIG. 4 to that shown in FIGS. 5 and 6, the wrench 122 will be pushed upwardly to the position shown in FIG. 5 if the wrench flats 124 are not in interfitting alignment with the flats 62a at the top of pipe section 3601. In most instances the wrench 122 will ride atop the upper pipe section due to the fact that, when the sub 100 and the section 36a are fully threaded together, as seen in FIG. 5, the flats 62a and 124 are seldom aligned to permit the wrench 122 to drop down into engagement with the pipe flats 62a. With the coupling 10 in the condition shown in FIG. 5, the drive unit 30 is reversely rotated and an unscrewing torque is applied to the upper section 36a by a reverse driving connection comprising the drive sleeve 82, the drive shaft 83 and the sub 100. At this time unscrewing will occur at one of two joints, i.e., either at the upper joint between the pipe sub 100 and the pipe section 36a, or at the lower joint between pipe sections 36a and 36b. If the lower joint is first to break, the problems enumerated above do not occur and the drive sleeve 82, the drive shaft 08 and the sub 100 provide the desired reverse driving connection between the drive unit 30 and the upper pipe section 36a. However, should the upper joint break first, as illustrated in FIG. 6, the present invention contemplates that the wrench 102 will engage the pipe flats in the manner shown in FIG. 6 just as soon as the upper section 36a unscrews from the sub 100 to the extent required to angularly align the wrench fiats 124 with the pipe flats 62a, as shown in FIG. 9. Thus the wrench 102 will shift down or telescope about the upper end of .pipe section 36:: to establish a positive connection between the external splines 84 of the drive sleeve 82 and the pipe flats 62a, thereby arresting further undesirable relative rotation between the pipe sub 100 and the pipe section 36a. Through this connection provided by the wrench 102, the unscrewing torque of the rotary drive unit 30 will be applied to the pipe section 3611 to cause the lower joint with pipe section 3611 to break and completely unscrew. From the foregoing description, it will be seen that the wrench 102 is conditioned to engage the pipe flats 62a by lowering the coupling 10 to the position shown in FIG. 5 and the actual engagement of the wrench and the pipe 62a flats occurs only if the upper pipe section 36a begins to unscrew from su'b 100, as shown in FIG. 6. It has been observed that the wrench 102 will drivably engage the pipe flats 62a within one quarter of a turn of the pipe 36a relative to the sub 100; therefore, the holding action of the wrench is applied to the pipe 36a before any substantial degree of unscrewing can occur at the aforementioned upper joint.

After the lower joint of pipe section 36a has been completely unscrewed, the drive unit 30 is raised to locate pipe section 36a in the mast 20 to be received in the pipe rack 42. In so raising the pipe section 36a, the coupling will be again extended to the position shown in FIG. 4 wherein pipe flats 62a drop out of engagement with the wrench 102. With the rack 42 swung in to receive pipe section 36a in an aligned slot 58, section 36a is lowered to seat in a socket 54. While section 36a is held against rotation in the socket 54 by a suitable means applied to flats 66a, the drive unit 30 is again reversely rotated to unscrew the upper joint between the sub 100 and the pipe section 36a thereby completing the disassembly of that section of the drill string 34. After the pipe rack 42 containing the disassembled pipe section is swung outwardly, the drive unit 30 is lowered to engage the neXt section of the string, i.e., section 36b and the pipe sub 100 is rotated forwardly to screw into the upper end of section 3612. The wrench head 70 is then released from flats 64b of section 36b and the drill string is raised in the mast in order that section 36b may be disassembled in the manner hereinbefore described in connection with section 36a. The disassembling process is continued until all pipe sections are stored in the rack 42 except the lowermost section which may be conveniently stored within the mast 20.

Those familiar with the structure and operation of topdrive drill rigs will readily appreciate that the herein described embodiment of the present invention provides several important advantages over known devices intended for the same purpose. First of all, the coupling 10 is connected in axial alignment with the drill string 34 and, in effect, becomes a part of the drill string itself inasmuch as the coupling is employed as a positive driving link between the rotary drive unit 30 and the drill string 34 during assembly of the string, during normal drilling operation, and during disassembly of the string. This is in eontradistinetion to known coupling and uncoupling tools which are generally applied to a pipe section in a radial direction, as in the case of automatic pipe tongs or pipe wrenches. Such prior art tools take up space within the mast, add weight at the top of the mast and require either special mechanical means for their control or manual positioning and manipulation. On the other hand, the telescoping wrench 102 of coupling 10 is compact, being only slightly greater in diameter than the pipe sections, and requires no special means for its actuation since operator-controlled raising and lowering of the rotary drive unit 30 rapidly and efficiently effects engagement and disengagement of the telescoping wrench 102. Moreover, due to the simplicity and ruggedness of construction of coupling 10, repair and maintenance costs are negligible and original manufacturing costs are low. Still another distinguishing feature of the coupling device 10 is its ability to act as a conduit for a hole flushing medium, such as compressed air, without appreciable internal restrictions which cause loss of pressure and impede fluid flow. Thus the coaxially aligned bores of the adapter 74, the drive sleeve 82, the drive shaft 88 and the pipe sub 100 provide an internal passage for the flushing medium of ample flow capacity.

Having fully described the invention, what is claimed as new and useful is:

1. A coupling device between a rotary driving member and a rotatably driven member comprising:

(a) a drive shaft axially shiftable but nonrotatable with respect to said driving member;

(in) said drive shaft being detachably secured to said driven member in driving relation thereto and for axial shifting therewith, detachment of said drive shaft and said driven member being effected by relative rotation therebetween;

(c) wrench means axially shiftable with respect to said driving member, said driven member and said drive shaft, but said wrench means being nonrotatable with respect to said driving member and said drive shaft;

((1) said wrench means being conditioned for shifting with respect to said driven member and into nonrotatable engagement therewith in response to axial shifting of said drive shaft and said driven member relative to said driving member.

2. The invention according to claim 1 wherein said coupling device includes a hollow drive sleeve nonrotatably attached to said rotary driving member; and

said drive shaft has an axially shiftable but nonrotatable connection with said drive sleeve and is coaxially surrounded by said drive sleeve.

3. The invention according to claim 2 wherein said wrench means has an axially shiftable but nonrotatable connection with said drive sleeve and coaxially surrounds said drive sleeve.

4. The invention according to claim 3 wherein said drive shaft and said wrench means are independently axially shiftable with respect to said drive sleeve between limiting axial positions.

5. The invention according to claim 4 wherein said driven member is threadably attached to one end of said drive shaft and is axially shiftable therewith; and

said wrench means is conditioned for axially shifting engagement with said driven member in response to axial shifting of said drive shaft to one limiting position.

6. The invention according to claim 5 wherein said wrench means and said driven member are provided with interfitting surface means which are engageable after said wrench means is conditioned as aforesaid and when said surface means are angularly aligned.

7. The invention according to claim 5 wherein said wrench means is disengaged from said driven member whenever said drive shaft is shifted to its other limiting axial position.

References Cited by the Examiner UNITED STATES PATENTS 2,054,223 9/1936 Le Bus 173164 2,624,549 1/ 1953 Wallace 64-23 2,809,014 10/1957 Lawrence et al. 173164 3,181,630 5/1965 Coburn 173164 3,239,016 3/1966 Alexander 173164 FRED C. MA'ITERN, JR., Primary Examiner. L. P. KESSLER, Assistant Examiner. 

1. A COUPLING DEVICE BETWEEN A ROTARY DRIVING MEMBER AND A ROTATABLY DRIVEN MEMBER COMPRISING: (A) A DRIVE SHAFT AXIALLY SHIFTABLE BUT NONROTATABLE WITH RESPECT TO SAID DRIVING MEMBER; (B) SAID DRIVE SHAFT BEING DETACHABLY SECURED TO SAID DRIVEN MEMBER IN DRIVING RELATION THERETO AND FOR AXIAL SHIFTING THEREWITH, DETACHMENT OF SAID DRIVE SHAFT AND SAID DRIVEN MEMBER BEING EFFECTED TO RELATIVE ROTATION THEREBETWEEN; (C) WRENCH MEANS AXIALLY SHIFTABLE WITH RESPECT TO SAID DRIVING MEMBER, SAID DRIVEN MEMBER AND SAID DRIVE SHAFT, BUT SAID WRENCH MEANS BEING NONROTATABLE WITH RESPECT TO SAID DRIVING MEMBER AND SAID DRIVE SHAFT; (D) SAID WRENCH MEANS BEING CONDITIONED FOR SHIFTING WITH RESPECT TO SAID DRIVEN MEMBER AND INTO NONROTATABLE ENGAGEMENT THEREWITH IN RESPONSE TO AXIAL SHIFTING TO SAID DRIVE SHAFT AND SAID DRIVEN MEMBER RELATIVE TO SAID DRIVING MEMBER. 